1. Field of the Invention
The present invention relates to surgical methods and devices to stabilize vertebra, and more particularly to surgical tools for physicians that are used to install spinal rods or longitudinal members and immobilizing cables between vertebrae.
2. Description of Related Art
Degenerative disc disease accounts for more than 100,000 low back spinal fusion procedures in the United States annually, according to Columbia, Colo. hospitals. The intervertebral disc is a pad of cartilage-type material situated between spinal bones. Each disc serves as a connector, spacer, and shock absorber for the spine. A soft, jelly-like center is contained by outer layers of fibrous tissue. Healthy discs help allow normal turning and bending. Trauma or injury to the spine can cause discs to tear, bulge, herniate, and even rupture. This can be quite painful, as the soft center of the disc leaks, putting pressure on the adjacent nerve roots and spinal cord.
A damaged disc can cause nerve dysfunction and debilitating pain in the back, legs and arms. Typical treatments that provide relief and allow patients to function again include back braces, medical treatment, physical therapy and surgery to remove the disc. A conventional surgical solution removes the bad disc and promotes new bone growth in the space to fuse the adjacent vertebrae together.
A few surgical procedures require the passing of loops of heavy 18-gauge wire or cable leader under the spinal lamina without disturbing the nerves or spinal cord. Each thoracic vertebrae in the back, for example, has a central hole (vertebral canal) through which the spinal cord naturally passes. There is a small space in the posterior corner, adjacent to the lamina, where a cable can be safely passed through. But just forward of this is the spinal cord which is very delicate and absolutely cannot tolerate being significantly disturbed. Neurologic injury has been associated with the passage of wires and cables in these locations.
What is needed is a safe way to pass through cables without running any risk of nicking or damaging the spinal cord or other nerves.
Once a cable has been passed, a device can be used to secure the cables, for example, like that described by Robert J. Songer, et al., in U.S. Pat. No. 5,116,340, issued May 26, 1992. Surgical cables looped through spinal vertebrae can be permanently secured by the crimping pliers of Songer.
An object of the present invention is to provide a surgical tool for the installation of vertebrae-immobilizing cables.
Another object of the present invention is to provide a method for the installation of vertebrae-immobilizing cables.
Briefly, a surgical tool embodiment of the present invention comprises a moderately flexible curved plastic rod with a loop snare at a distal end. The tool is used to pass a size-1 or size-0 suture through the triangular cross-sectional area behind the spinal cord and inside between the ligamentum flavum on both posterior sides. The suture is then, in turn, used as a pilot-line to pull through a much heavier spinal cable or wire. Such tool is supplied sterile and is disposable, and one-millimeter polyethylene material is preferred. Such cable is connected with other cables and rods to immobilize portions of the spine.
A method embodiment of the present invention for installing spine-stabilization components comprises directing a long plastic flexible tool through a sublaminar space of a human spine vertebrae inside the spinal canal. Such tool enters the sublaminar space of a particular one of the human spine vertebrae posteriorly from the intervertebral gap with an adjacent vertebrae. It exits the sublaminar space of the particular one of the human spine vertebrae posteriorly from the intervertebral gap with another opposite-side adjacent vertebrae. A suture is threaded through an eye of the tool. The suture is pulled back through the sublaminar space by withdrawing the long plastic flexible tool. The suture is detached from the long plastic flexible tool. A pulled-through part of the suture is attached to a spinal-fixation wire or cable. The suture is then usable as a pilot-line to draw the spinal-fixation wire or cable safely through the sublaminar space. The spinal-fixation wire or cable is used to anchor a spinal-fixation system.
An advantage of the present invention is that a surgical tool is provided that simplifies the installation of surgical cables in the spine.
Another advantage of the present invention is that a method is provided that makes it safer to install cables and rods to immobilize damaged portions of the spine.